Quite frankly, it is worth pointing out this might bring some disadvantages for players that do use grass, but unfortunately on some systems (like mine) it is simply impracticable to leave grass on.
I think most people would like to have it, as it adds so much more authenticity to the environment... but for the moment Rust is a light game that runs on most computers, even laptops, and that is one of the perks in it compared to the ArmA series / DayZ for instance.
However, as there is no way for the player to go prone, the amount of cover grass provides is arguably minor.
Perhaps a solution to please all parties would be to add this "force grass" feature as a server option?
Pretty much what Vilusia said. I can see if people are running pretty old system's it wouldn't be fair on them. In some places the grass is higher than crouch height so I think it's higher than minor but nothing like prone for sure.